Ignition system for internal combustion engines and the like



Sept. 2, 1969 B. o. BURSON 3,464,37

IGNITION SYSTEM FOR INTERNAL COMBUSTION ENGINES AND THE LIKE Filed Jan. 23, 1967 2 Sheets-Sheet 1 p 1969 B. o. BURSON 3, 64,377

IGNITION SYSTEM FOR INTERNAL COMBUSTION ENGINES AND THE LIKE Filed Jan. 23, 1967 2 Sheets-Sheet 2 York Filed Ian. 23, 1967, Ser. No. 614,385 Int. Cl. F02 3/02, 7/00; H051) 41/14 US. Cl. 123-148 26 Claims ABSTRACT OF THE DISCLOSURE An ignition system for an engine with an ignition device is provided having flux generating means on a rotatable part of the engine. A first winding is supported by a non-rotatable structure and cooperable with the flux generating means for generating pulses. Charge storage means is provided and first rectifier means connects the charge storage means to the first winding. Switch means is responsive to a control signal for connecting the charge storage means to the ignition device. A second winding is supported on a non-rotatable structure and cooperable with the flux generating means to generate a control signal. Second rectifier means connects the second winding to the switching device for actuating the switching device.

The present invention relates to an ignition system for an internal combustion engine, and particularly to improvements in such systems in which the conventional battery ignition system is replaced by electronic circuitry.

There are many applications in which it is desirable to provide a companct ignition system for use with light, portable engine devices, such as, engines for boats, garden tractors, snow plows, law mowers and the like. Such systems are preferably designed without the use of a battery in order to further the aim of lightness and compactness and to avoid the need for carrying a separate battery system. The present invention relates to such an ignition system which employs a simple magneto arrangement and a few simple circuit elements in its preferred embodiments. The present invention preferably employs the flywheel, or some other rotatable part of the engine, as part of the magneto with permanent magnet flux generating means attached to the flywheel. In this manner the flux generating portion of the magneto is synchronously operated with the engine at all engine speeds and may be advantageously employed along its path of travel with the flywheel or other part to actuate one or more components of the ignition system.

There are also many applications in which it is desirable to provide an ignition system with advance and retard pulse generating means coupled to the fuel igniting means for igniting combustible fuel in the engine. During the cranking cycle of an internal combustion engine, it is desirable for the ignition spark to occur at some point near top dead center on the compression stroke of the engine piston. After the engine has started and reached a predetermined speed, it is then desirable to have the ignition spark occur at a predetermined point before the piston reaches top dead center of its compression stroke. The former of these two conditions is commonly referred to as retard spark and the latter as advance spark.

More particularly, in the cranking cycle, a retard spark condition is desirable to prevent the occurrence of firing of the piston prior to the piston reaching its top dead center position, because there is a tendency for the piston under such circumstances to be forced back downward while on the compression stroke, thereby tending to reverse the normal direction of rotation of the crank shaft. On large hand started engines, the latter occurrence is States Patent 3,464,397 Patented Sept. 2, 1969 dangerous in that the handle starting the device may be jerked from the operators hand resulting in injury to the operator. Further, a retard spark condition allows the engine to be started more easily. Once the engine has started and reached a predetermined speed, however, it will operate more efliciently if firing of the piston occurs at some point prior to the piston reaching top dead center. The advance spark condition is then desirable since the piston is traveling at a higher speed and in order for full combustion to occur at or near top dead center of the piston, it is necessary to start combustion at some point prior thereto.

In the prior art, systems have been designed to provide advance and retard spark conditions for firing the fuel igniting means of the engine. For the most part, these systems have employed mechanic-a1 advance mechanisms, such as, devices controlled by engine vacuum or mechanically operated advance devices. These systems have not been as simple and inexpensive as desirable for providing optimum operation of the engine.

In accordance with the present invention, a new and improved ignition system with novel features is provided which cooperate to facilitate a compact, economical and reliable system. The ignition system of the present invention is designed to be employed with an engine having at least one spark gap ignition device. The ignition system of the present invention comprises magnetic circuit means having flux generating means, which is preferably provided by at least one magnet mounted on a rotatable part, such as the flywheel, of the engine. There is employed a first winding supported on a portion of the magnetic circuit means on the non-rotatable structure adjacent the flywheel so that the winding is cooperable with the flux generating means to provide a means for generating voltage pulses each revolution of the flywheel, Also employed is charge storage means and first rectifier means for connecting the charge storage means to the first winding to charge the charge storage means only by current of one polarity flowing in the first winding. Switching means is provided which is responsive to a control signal for connecting the charge storage means to the ignition device.

Also employed is a second winding supported on a portion of the magnetic circuit means on a non-rotatable structure adjacent the flywheel at a position along the path of travel of the flux generating means from the first winding. The second winding is cooperable with the flux generating means to provide means for generating a control signal each revolution of the flywheel. Second rectifier means is provided for connecting the second winding to the switching means to have one polarity of the control signal applied to the switching means to cause the switching means to connect the charge storage means to the igniting means for firing the ignition device.

In accordance with a further feature of the present invention, timing means is provided which is operable for regulating in accordance with engine speed the time at which the switching means is caused to connect the charge storage means to the ignition device. In one embodiment of the invention, the timing means comprises a third winding supported on a portion of the magnetic circuit means on a non-rotatable structure adjacent the flywheel along the path of travel of the flux generating means at a position in a range extending between and including the positions of the first and second windings. This third winding is cooperable with the flux generating means to provide a means for generating a control signal each revolution of the flywheel. Third rectifier means is employed for connecting the third winding to the switching means to have one polarity of its control signal applied to the switching means to cause the switching means to connect the charge storage means, to the ignition de- J vice. In this arrangement, means for regulating the actuation of the switching means is employed such that the control signal actuating the switching means is supplied alternatively from the second winding or from the third winding in accordance with engine speed to provide a re- 7 tard or advance spark, respectively, at the ignition device.

For a better understanding of the present invention, reference is made to the following drawings, in which:

FIG. 1 is a schematic diagram of an ignition system embodying one form of the present invention;

FIG. 2 is a schematic diagram of an alternative form of a portion of the electrical system of FIG. 1;

FIG. 3 is another schematic diagram of an alternative form of a portion of the electrical system of FIG. 1;

FIGS. 4, 5, 6, 7 and 8 are reduced fragmentary views illustrating the flywheel, magnets and windings of FIG. 1 and showing successive positions of the flywheel and magnets for generating voltage pulses in the windings;

FIG. 9 is a schematic diagram of an ignition system embodying another form of the present invention;

FIGS. 10a, 10b, 10c and 10d are idealized graphical illustrations of the voltage waveforms which occur across various components of the circuit of FIG. 1 during intervals of movement of the magnets indicated in FIG. 1; and

FIGS. 11a, 11b, 11c and 11d are idealized graphical illustrations of the voltage waveforms which occur across various of the components of FIG. 9 during intervals of movement of the magnets indicated in FIG. 9.

Referring to FIG. 1, a detailed schematic diagram of the circuitry and structure of a system embodying one form of the present invention is shown. The ignition system is used in conjunction with an engine (not shown) which may be a conventional gasoline engine. For purposes of illustration, it will be assumed that the engine is of the four-cycle type and has one cylinder which is provided with an associated spark gap ignition device for igniting combustible fuel in the cylinder. As is conventional in ignition systems, an inductive means may be coupled to the spark gap ignition device for generating sufficient potential to produce a spark at the device. In the present instance, as shown in FIG. 1, the inductive means is provided by a voltage step-up transformer, generally designated 10, having a primary winding f2 and a secondary winding 14, which has associated with it a spark plug 16, a spark gap ignition device in accordance with the present invention. Current which flows in the primary winding of the transformer induces a very high voltage in the secondary winding sutficient to fire the spark plug, which has one of its terminals connected to electrical ground and the other connected to the high potential end of secondary winding 14.

The voltage pulses used to fire the spark plug are generated by a magneto induction generator, generally designated 20, which includes magnetic flux generating means on a rotor and a winding on a stator. More specifically, the magneto induction generator comprises a. rotor assembly 22 including a pair of permanent magnets 24 and 26 with north and south poles as designated thereon, magnet 26 being arranged to produce the reverse flux polarity at the exposed pole faces, and, in the present instance, a flywheel 28 of the engine having a cylindrical rim 28a, which has the magnets 24 and 26 attached thereto on the underside of the rim. The flywheel is keyed to engine crank shaft 30, as shown in the re duced fragmentary view of the flywheel in FIG. 4. The flywheel is preferably employed to support the magnets since it provides a relatively large path of movement for the magnets and provides rapid movement of the flux generating magnets for inducing desired voltage pulses in winding assemblies supported on non-rotatable structures along the path of travel of the magnets. Other rotatable parts of the engine could be employed for supporting the flux generating magnets if desired. The proper timing relation for firing of the fuel in an engine cylinder is regulated by the flywheel rotating in synchronism with the crank shaft, which produces the proper relationship between the rotating system which drives the pistons and the occurrence of each pulse supplied for firing the ignition device.

As shown in FIG. 1, the flywheel and magnet assembly rotates closely adjacent a stator winding assembly, generally designated 32, fixedly supported relative to the flywheel on the engine frame. The stator winding assembly 32 may comprise a generally E-shaped stator member 33 fixedly positioned in close proximity to rim 28a of the flywheel with the legs of the stator member projecting in close proximity to the path of travel of the magnets to be adjacent the magnets once each revolution of the flywheel to complete a magnetic circuit. The spacing of the legs of the generally E-shaped stator generally corresponds to the spacing between the magnets 24 and 26 on the flywheel.

A first output winding 34 of the magneto induction generator is wound on the center leg of the E-shaped stator member. Making the stator member all one piece and of a general E-shape shown is a matter of design choice. As the flywheel and magnet assembly rotates about the axis of the engine crank shaft, an alternating magnetic flux is induced in the stator member causing a buildup and collapse of flux lines within the first output winding 34, resulting in an induced voltage in first output winding 34. Voltages of alternately opposite polarity in immediate sequence are induced in first output winding 34 once each complete revolution of the flywheel, which comprises movement of the flywheel on the crank shaft through 360.

The voltage pulses from first output winding 34 are rectified in a manner to produce at capacitor 40, or any other suitable charge storage means, voltage pulses of one polarity for charging capacitor 40. The rectifying means for this purpose is provided by connecting one end of the output Winding to electrical ground and the other end to the anode of a diode 42, which has its cathode connected to capacitor 40. The positive voltage pulses registered across capacitor 40 are blocked from discharging by diode 42 to maintain the charge across the capacitor until a predetermined time when the capacitor is discharged through the spark gap ignition device. The negative pulses produced in first output winding 34 by the magnets are blocked by diode 42 from creating a voltage across capacitor 40 and are absorbed in a circuit connected across winding 34. The latter circuit comprises a diode 44 having its cathode connected between the output winding and diode 42, and a resistor 46 connecting the anode of diode 44 to electrical ground. The capacitor 40 will be charged by positive pulses from the winding through diode 42 unless the kill switch 50 is closed to connect the normally charged side of capacitor to electrical ground so that both sides of the capacitor are grounded and no charging is possible.

The charge storage capacitor 40 is electrically connected to primary winding 12 of step-up transformer 10 through switching means 52 for providing a pulse to fire spark plug 16. In the present instance, the switching means 52 preferably comprises a silicon-controlled rectifier which has its anode element connected to the charged side of capacitor 40, and its cathode element connected to primary winding 12. The control terminal 52a of the silicon-controlled rectifier is responsive to a control signal to turn on the rectifier, which then acts like a closed switch to provide a circuit between the capacitor and the transformer so that current may flow from the charged capacitor to the transformer for firing the spark plug in a conventional manner.

The control signal for switching silicon-controlled rectifier 52 is produced by triggering induction generator, generally designated 54, and is applied between the control terminal and cathode element of the rectifier 52, as a positive potential at the control terminal. The magnetic fiux generating means for triggering induction generator 54 is provided by the magnets 24 and 26 mounted on the flywheel. In the present instance, the magnets are rotated in close proximity to second and third induction windings 56 and 58 wound on a common core stator member 60, which completes a magnetic circuit with the magnets and which may be secured to the engine frame by any suitable means along the path of travel of the magnets. As the flywheel rotates the magnets, magnetic flux through core member 60 increases and decreases, resulting in an induced voltage in each of windings 56- and 58 wound on core member 60. As shown in FIG. 1, windings 56 and 58 are wound in opposite directions so that as a positive pulse or control signal is induced in one of the windings, a negative pulse or control signal will be induced in the other of the windings. One end 56a and 58a of windings 56 and 58, respectively, is connected to a common terminal, which is connected to the control terminal 52a of rectifier 52. The other ends 56b and 58b of windings 56 and 58, respectively, are connected through separate rectifier means to the cathode element of rectifier 52 in a manner to produce a control signal of the same polarity between the control terminal and cathode element during alternate sequential intervals as the magnets pass by core member 69. The rectifier means for the windings are provided by having end 56b of winding 56 connected to the cathode of diode 62, which has its anode connected to the cathode element of rectifier 52, and end 58b of winding 58 connected to the cathode of diode 64. The anode of diode 64 is connected to the anode of Zener diode 66, which has its cathode connected to the cathode element of rectifier 52.

The second and third windings 56 and 58 and their associated circuits connected to the control terminal of rectifier 52 provide a means for causing spark at the ignition device at different intervals in accordance with engine speed. The third winding 58 and its circuit provides a timing means for regulating the time at which the switching means is caused to connect the capacitor with the ignition means, and, more particularly, provides an advance spark for firing the spark plug at engine speeds in excess of a predetermined level. The means for regulating the actuation of the switching means alternatively from the control signal of the winding 56 or the control signal of winding 58 in accordance with engine speed is the Zener diode connected in the circuit of winding 58. The Zener diode limits the control signal from winding 58 so that it is not effective to cause switching of the rectifier 52 until the engine has reached a predetermined speed, as will be explained more fully hereinafter. The means for regulating the actuation of the switching means alternatively from the control signal of winding 56 or winding 58 could be provided by having winding 56 of more turns of conductor than winding 58 so that the engine would have to reach a predetermined speed before the control signal from winding 58 would be of sufificient value to cause switching of rectifier 52. In this latter arrangement, Zener diode 66 could be eliminated, but for optimum operation in providing a definite speed at which advance spark will occur, the Zener diode is preferably employed.

In operation of the system of FIG. 1 at slow engine speeds, when the engine piston is nearing a position for which its associated spark plug is to be fired, the permanent magnets attached to the flywheel, which is assumed to be rotating in a clockwise direction as indicated in FIG. 1, will be approaching winding assembly 32. As the leading edge of magnet 24, which produced flux of one polarity, moves from T to point T during time interval A in FIG. 1, a negative voltage is induced in first output winding 34. The negative pulse induced in output winding 34 is blocked from charging capacitor 40 by diode 42.

When the leading edge of magnet 24 has moved from point T shown in FIG. 1 to point T shown in FIG. 4, indicated by the interval B in FIG. 4, flux reversal occurs in output winding 34 to induce maximum positive voltage in the output winding. A positive voltage is induced in the winding when the end 34a thereof is positive with respect to end 34b. In this instance, positive current can flow from the winding through diode 42 to capacitor 40 to charge the capacitor, but cannot pass through switching means 52, since it is effectively open and will not pass current.

FIGS. 10a, 10b, 10c and 10d are graphical illustrations of voltage waveforms which occur across various components of the circuit in FIG. 1 as magnet 24 moves from points T to T1, T1 to T2, T2 to T3, T3 to T4, T4 to T5, T to T indicated by the intervals A, B, C, D, E and F, respectively, in FIGS. 1, 4, 5, 6, 7 and 8, respectively. The waveforms shown are idealized waveforms to show the principal effect of the voltages considered. More specifically, in FIG. 1011 the solid line Waveform V indicates the voltage across charge storage capacitor 40 as indicated by V, in FIG. 1. In FIG. 10b the solid line waveform V represents the voltage across winding 56 as indicated by V in FIG. 1. In FIG. 10c the solid line waveform V represents the voltage across winding 58 as indicated by V in FIG. 1. The dotted line above the zero voltage level in FIG. represents the voltage level which must be induced across winding 58 before Zener diode 66 will pass current to permit positive current to flow from the winding 58 to control terminal 52a. In FIG. 10:! the solid line waveform V represents the voltage between the control terminal and cathode element of the silicon-controlled rectifier 52 as indicated by V; in FIG. 1. The dotted line above the Zero voltage level in FIG. 10d indicates the voltage level which must be reached between the control terminal and cathode element before the rectifier will be switched to connect the charged capacitor to the ignition device. The voltage waveforms V V V and V shown in solid lines in FIGS. 10a, 10b, 10c, and 10d represents the successive voltages which appear across the points in the circuit in FIG. 1 marked V V V and V, at slow engine speeds; and the dotted line waveforms V V V and V represent the successive voltages which appear at corresponding places without primes in the circuit in FIG. 1 at high engine speeds.

At slow engine speeds, when the magnets on the flywheel move from the position shown in FIG. 1 to the position shown in FIG. 4, during the interval B, the positive voltage induced in output winding 34 will cause a current to flow to capacitor 40, charging the capacitor to a voltage as indicated by the voltage waveform V in FIG. 10a during the interval B.

During the interval C, the permanent magnets on the flywheel move from the position shown in FIG. 4 to the position shown in FIG. 5, where the magnets are approaching windings 56 and 58. When the magnets are moved from the position shown in FIG. 5 to the position shown in FIG. 6, indicated by the interval D, a negative voltage is induced across winding 56 and a positive voltage is induced across winding 58, the magnet 24 producing a flux of one polarity through the windings. It will be recalled that windings 56 and 58 are wound in opposite directions on the common stator member so that when a positive polarity pulse is induced in one winding, a pulse of the opposite polarity will be induced in the other winding. During the interval D, negative voltage is induced across winding 56 as shown in FIG. 10b by the solid line waveform V at the same time a positive voltage is induced across winding 58 as shown in FIG. 10c by the solid line waveform V The negative voltage induced across winding 56 is blocked from causing a current to fiow in its circuit by diode 62. The Zener diode 66 in the circuit of winding 58 blocks current until a predetermined voltage potential is induced in that winding. Since the voltage induced in winding 58 during the interval D, as shown by waveform V does not exceed the predetermined voltage potential necessary to cause current to flow through the Zener diode, there is no voltage potential from winding 58 applied between the control terminal 52a and the cathode element of rectifier 52, during the interval D, as shown in FIG. d.

When the magnets on flywheel 28 move from the position shown in FIG. 6 to the position shown in FIG. 7, indicated by the interval E, flux reversal occurs in windings 56 and 58, and, as a result, a positive voltage is induced across winding 56 and a negative voltage is induced across winding 58, as indicated by the voltage waveforms at V and V during the interval E in FIGS. 10b and 10c. The negative voltage induced across coil 58 is blocked from causing a current to flow in its circuit by the diode 64. However, the positive voltage induced across winding 56 (end 56a being positive with respect to the opposite end of the winding) causes a current to flow through diode 62 thereby having the control terminal positive with respect to the cathode element of rectifier 52.

In this instance, the voltage potential between the control terminal and cathode element is above the switching level of the rectifier, as indicated at V during the interval E in FIG. 10d so that the rectifier is switched to connect the capacitor to the transformer 10. At this time, the charged capacitor 40 will discharge suddenly causing a current to fiow through the rectifier into the primary winding of the transformer to generate a high voltage pulse in the transformer secondary to fire the spark plugs 16.

During the interval F the magnets are moved from the position shown in FIG. 7 to the position shown in FIG. 8. Upon this occurrence slight voltages of opposite polarities, corresponding to those in interval D, are induced in windings 56 and 58, but the voltages are of no consequence to the operation of the system since the capacitor has already been discharged to fire the spark plug. It should be appreciated that the flywheel with the attached magnets will rotate around to a position as shown in FIG. 1 and the cycle will repeat itself.

The operation of the system for fast engine speeds is similar to the operation previously described in regard to the slow speed operation of the system. At high speed operation of the engine, it is desirable to provide an advance spark to fire the spark plug on the compression stroke of the piston before to dead center of the piston stroke is reached. It will be recalled that at slow speed operation the piston is fired during the interval E and that the voltage generated in winding 53 during the previous interval D is not sufficient to actuate the switching means to fire the spark plug. However, at high speed operation of the engine the flywheel will be rotated faster so that the rate of change of flux lines from the magnets through windings 56 and 58 will be greater to induce larger voltages across the windings. Thus, at the high engine speed, during the interval D in FIG. 6 the voltage induced in winding 58 is greater and is above the break down voltage of the Zener diode 66, as shown by the voltage waveform V during the interval D in FIG. 10c. This increased voltage generated in winding 58 is sulficient to provide the necessary positive potential at control terminal 52a of rectifier 52 to cause switching of the rectifier, as shown by the voltage waveform V during the interval D in FIG. 10d, so that the capacitor 40 may discharge through the rectifier and the primary winding of the transformer to fire the spark plug during the interval D. The increased voltages induced in the windings are indicated in FIGS. 10b and 10c by the dotted line waveforms V and V respectively, during the interval D, and the increased voltages applied across the capacitor and between the control terminal and cathode element of rectifier 42 are indicated in FIGS. 10a and 10d by the dotted line waveforms V and V respectively. At high speed operation after rectifier 52 has been actuated during the interval D, the induced voltages during the intervals E and F in windings 56 and 53 also are sufficient to actuate the rectifier, but since the capacitor has previously been discharged, these latter occurrences have no effect on the ignition device.

FIG. 2 illustrates an alternative form for the triggering induction generator 54 of FIG. 1. The triggering induction generator shown in FIG. 2 for switching the silicon-controlled rectifier 52 is a simplified version in that it has only one triggering winding. The sub-system of FIG. 2 can be employed on engines which are suitably operated without the advance and retard spark conditions, while providing an ignition system which is rugged in design and employs few parts for an inexpensive system and one which is easy to assemble. The subsystem of FIG. 2 is substituted for the part of the system of FIG. 1 within the dashed line box 54. The triggering induction generator of FIG. 2 comprises a stator core member having a winding 102 wound on the core. A diode 104 for rectifying the signal from winding 102 is provided in series with one end of the winding, connecting winding 102 to the cathode element of rectifier 52 (shown in FIG. 1), and the other end of winding 102 is indicated connected to the control terminal of rectifier 52.

The general operation for winding 102 and diod 104 of FIG. 2 is the same as the operation of winding 56 and diode 62 of FIG. 1. As the magnets on the flywheel approach the winding 102, after the capacitor has been charged, a negative voltage will be induced in Winding 102 so that end 102a of the winding 102 will be negative with respect to the other end. The negative voltage induced in the winding will not cause a current to flow in the circuit since diode 104, as connected, will not pass the current. As the flywheel continues to rotate the magnets, a positive voltage will be induced in winding 102, making end 102a of the Winding positive with respect to the other end, so that a current will flow in the circuit through diode 104. The voltage at the control terminal is suflicient to switch the rectifier to allow the capacitor to discharge for firing of the spark plug. The positive voltage induced in winding 102 during this interval has a waveform similar to the waveform V during interval E of FIG. 10b to switch the silicon-controlled rectifier to pass current. This cycle repeats itself each revolution of the flywheel for firing of the spark plug.

FIG. 3 illustrates still another form for the triggering induction generator 54 of FIG. 1. The induction generator shown in FIG. 3 is a simplified version in that it has only one triggering winding 110, in a manner similar to the embodiment shown in FIG. 2. The triggering induction generator of FIG. 3 thus does not provide the advance and retard conditions of firing for the spark plug, but merely shows another arrangement for connecting the diode associated with the single triggering winding.

e sub-system of FIG. 3 is substituted for the part of the system of FIG. 1 within the dashed line box 54. In this intsance, the winding is wound on a stator core member 111 which may be fixed to the engine frame by any suitable means. The winding is connected to the silicon-controlled rectifier 52 (shown in FIG. 1) by having end 110a of the winding connected to the control terminal and end 1101) connected to the cathode element of the rectifier. There is connected across the winding 110 a diode 112 having its anode connected to side 1101; of winding 110 and its cathode connected to side 11011.

As the magnets on flywheel 28 approach the core member on which winding 110 is wound after the capacitor 40 has been charged, a negative voltage is induced in winding 110, end 110a being made negative with respect to end 1101;. In this instance, diode 112 will permit flow of current therethrough to short circuit winding 110. AS the magnets on thefiywheel are further rotated, a positive voltage will be induced in winding 110, Upon this occurrence, diode 112 will be in its non-conductive state and the control terminal of the rectifier will be made positive with respect to the cathode element to switch the silicon-controlled rectifier to discharge the capacitor through the transformer to fire the spark plug. The voltage induced in winding 110 during this interval has a waveform similar to the waveform V during interval E of FIG. 10b to provide sufiicient voltage to switch the rectifier to pass current from the capacitor.

Referring to FIG. 9, a schematic diagram of an ignition system is shown embodying another form of the triggering induction generator 54 of FIG. 1. In the modified system of FIG. 9, parts similar to those in the system of FIG. 1 are identified by the same number designators with the addition of primes thereto. The primary difference between FIGS. 1 and 9 lies in the triggering induction generator 54', shown in FIG. 9, for providing the advance and retarded spark conditions of the ignition system for preferred operation of the engine. In the present instance, the triggering induction generator 54 comprises second induction winding 120 wound on stator core member 122, which may be secured to the engine frame by any suitable means. Stator assembly 122 with winding 120 is spaced from first output winding 34 at a position along the path of travel of the flywheel to be cooperable with the magnets to generate a control signal for switching the rectifier 52', so that the spark plug is fired in the engine cylinder near top dead center of movement of its piston.

The triggering induction generator 54 is provided with third induction winding 124 wound on stator core member 126, which may be secured to the engine frame by any suitable means. Third winding 124 on core 126 is employed to provide an advance spark for the ignition device for operation at high engine speeds, thereby providing a means for better timing in firing of the spark plug. The third winding 124 may be located at a position in a range extending between and including the positions of first and second windings to provide the advance spark. For example, in FIG. 1 the two triggering induction windings 56 and 58 are located on a common stator core, whereas in FIG. 9 third winding 124 for providing advance spark is positioned along the path of travel of the magnets generally between first winding 34 and second winding 120. The timing for providing the retard and advance spark for firing of the ignition device can be adjusted by the relative positioning of output winding 34', winding 120 and winding 124. The means for regulating the actuation of silicon-controlled rectifier 52 alternatively from the control signal of second winding 120 or the control signal of third winding 124 is provided by having winding 124 of fewer turns than winding 120, so that the engine has to reach a predetermined speed before the control signal from third winding 124 is of sufl'icient potential to cause switching of rectifier 52 for the advance spark.

The windings 120 and 124 are connected in generator circuit 54 with end 120a of winding 120 and end 124a of winding 124 connected together at a terminal, which is connected to control terminal 52a of silicon-controlled rectifier 52. The other end 12012 of winding 120 is connected to the cathode of diode 128, which has its anode connected to cathode element of rectifier 52'. The other end 1241) of winding 124 is connected to the cathode of diode 130, which has its anode connected to the cathode element of rectifier 52'.

FIGS. 11a, 11b, 11c and lld are graphical illustrations, similar to FIGS. 10a, 10b, 10c and 10d, of idealized voltage waveforms to show the principal effect of the voltages which occur across various components of the circuit of FIG. 9 during successive intervals as the center of magnet 24 moves from points T, to T T to T T2 to T3, T3 to T4, T4 to T5, T5 to T6, T6, to T7, and T to T indicated by the intervals A, B, C, D, E, F, G and H, respectively, in FIG. 9. More specifically, in FIG. 11a the solid line waveform V represents the voltage at specific intervals across capacitor 40 as indicated by V in FIG. 9. In FIG. 11b the solid line waveform V represents the voltage across winding 124 as indicated by V in FIG. 9. In FIG. 110 the solid line waveform V represents the voltage across winding as indicated by V; in FIG. 9. In FIG. 11d the solid line waveform V represents the voltage between the control terminal and cathode element of the silicon-controlled rectifier 52 as indicated by V in FIG. 9. The dotted line above the zero voltage level in FIG. 11d indicates the voltage level which must be reached between the control terminal and cathode element before the rectifier will be switched to connect the charged capacitor to the ignition device. The voltage waveforms V V V and V shown in solid lines in FIGS. lla, 11b, 11c and 11d, respectively, represent the successive voltages which appear across the points in the circuit of FIG. 9 marked V V V and V at slow engine speeds; and the dotted line waveforms V V V and V represent the successive voltages which appear at corresponding places without primes in the circuit in FIG. 9 at high engine speeds.

In operation of the system of FIG. 9 at slow engine speeds, after capacitor 40 has been charged, the magnets will move during the interval C to complete a magnetic circuit to induce a negative voltage in winding 124, end 124a being made negative with respect to end 124b, so that no current will flow through diode 120. During the interval D, a positive voltage is induced in winding 124, having a voltage waveform as indicated by V in FIG. 1112 during interval D, but the potential at slow engine speeds is not sufiicient to cause switching of the rectifier, as indicated by the waveform V shown in FIG. 11d during interval D. The negative voltage induced in winding 120 during interval F, making end 120a negative, is blocked from causing current flow by diode 128. The positive voltage induced in winding 120, which has more turns of conductor than winding 124, during interval G, is of suflicient value to cause switching of rectifier 52, as indicated at V during interval G, so that capacitor 40 may discharge to fire the spark plug.

At high speed operation of the engine, the positive voltage induced in winding 124 during interval D is of sutficient value to cause switching of the rectifier, as indicated by the dotted line voltage waveform V during interval D in FIG. 11d. This advanced switching of the rectifier at high engine speeds enables the advance spark for the ignition device. After the capacitor has been discharged during interval D, the cycle will repeat itself when the flywheel rotates the magnets back to the output winding 34 to again charge capacitor 40.

The speed at which the ignition system in FIG. 9 is regulated to change from retard spark to advance spark, and vice versa, depends, in this instance, on the number of turns of conductor in winding 124, the rate of rotation of the flywheel, the size and intensity of the flux generating magnets, the spacing between the magnets and windings, and the switching level of silicon-controlled rectifier 52. The optimum arrangement for any particular application will depend upon the engine involved and may be determined by known procedures.

Although for purposes of illustration a one cylinder engine, such as an outboard boat engine, has been described, it will be apparent to those skilled in the art that the ignition system of the present invention could be employed with a multi-cylinder engine by simply adding additional and similar components represented herein. Also, a mechanical distributor could be employed and an increased number of flux generating magnets on the flywheel, so that only one silicon-controlled rectifier, step-up transformer and charge storage capaictor would have to be employed. The number of magnets employed on the flywheel or the number of similar functioning windings, to those shown and described, may have to be increased depending on the number of cylinders of the engine.

It will be observed that the ignition system of the present invention provides a simple and inexpensive structure employing few parts. The magnetic flux generating means is simply provided by magnets preferably mounted on the flywheel and windings are fixed relative to the flywheel to have voltages induced therein by the rotating magnets. The ignition system employs simple circuitry for producing the desired pulse at the proper time for firing the desired spark plug of the engine. Moreover, with two triggering windings and a few circuit components, there is provided an ignition system with retard and advance sparks for optimum operation of the engine at slow and high speeds.

While the invention has been described with particular reference to specific embodiments thereof in the interest of complete definiteness, it will be understood that it may be embodied in a large variety of forms diverse from the ones especially shown and described, without departing from the scope and spirit of the invention as defined by the appended claims.

I claim:

1. An ignition system for an engine employing at least one spark gap ignition device, comprising:

magnetic circuit means adapted to be mounted on a rotatable part of the engine and a non-rotatable structure;

a first winding fixedly supported on the portion of the magnetic circuit means on the non-rotatable structure and cooperable with a portion of the magnetic circuit means on the rotatable part to produce flux of a polarity through the first winding for generating voltage pulses therein;

charge storage means;

first rectifier means for connecting the charge storage means to the first winding;

switching means responsive to a control signal to connect the charge storage means to the ignition device;

a second winding fixedly supported on the portion of the magnetic circuit means on the non-rotatable structure at a position along the path of travel of the same portion of the magnetic circuit means on the rotatable part as cooperates with the first winding and cooperable with the same portion of the magnetic circuit means on the rotatable part to produce the same flux polarity as through the first winding or the reverse flux polarity through the second winding to generate a control signal therein; and

second rectifier means for connecting the second winding to the switching means.

2. The ignition system of claim 1 in which the switching means includes at least one solid state: device.

3. The ignition system of claim 1 in which the magnetic circuit means includes at least one permanent magnet.

4. The ignition system of claim 1 further comprising timing means operable for regulating in accordance with engine speed the time at which the switching means is caused to connect the charge storage means to the ignition device for causing a spark at the ignition device.

5. An ignition system for an engine employing at least one spark gap ignition device, comprising:

magnetic flux generating means adapted to be mounted on a rotatable part of the engine;

a first winding fixedly supported on a non-rotatable structure adjacent the rotatable part and cooperable with the flux generating means for generating voltage pulses therein each revolution of the rotatable part;

charge storage means;

first rectifier means for connecting the charge storage means to the first winding to charge the charge storage means by current of one polarity flowing in the first winding;

switching means responsive to a control signal to connect the charge storage means to the ignition device;

a second winding fixedly supported on a non-rotatable structure adjacent the rotatable part at a position along the path of travel of the flux generating means from the first winding and cooperable with the flux generating means to generate a control signal each revolution of the rotatable part;

second rectifier means for connecting the second winding to the switching means to have one polarity of the control signal applied to the switching means to cause the switching means to connect the charge storage means to the ignition device; and

timing means operable for regulating the time at which the switching means is caused to connect the charge storage means to the ignition device, the timing means comprising a third winding fixedly supported on a non-rotatable structure adjacent the rotatable part along the path of travel of the flux generating means at a position in a range extending between and including the positions of the first and second windings and cooperable with the flux generating means to generate a control signal each revolution of the rotatable part, and third rectifier means for connecting the third winding to the switching means to have one polarity of the output from the third winding applied to the switching means to cause the switching means to connect the charge storage means to the ignition device, and means for regulating the actuation of the switching means alternatively from the control signal of the second winding or the control signal from the third Winding in accordance with engine speed.

6. The ignition system of claim 5 in which the second and third windings are wound on a common stator of magnetic material.

7. The ignition system of claim 5 in which a separate stator of magnetic material is provided for each winding and the third winding is located such that the flux generating means generates pulses in the first, third and second windings successively.

8. The ignition system of claim 5 in which the means for regulating the actuation of the switching means comprises a Zener diode in the circuit of the third rectifier means.

9. The ignition system of claim 5 in which the means for regulating the actuation of the switching means is provided by having the third winding of fewer turns than the second winding, and the third winding having its control signal generated therein after the first winding and before the second winding as the flux generating means rotates, the signal generated in the second winding being capable of causing the switching means to connect the charge storage means to the ignition device at all speeds of engine operation, the signal generated in the third winding being capable of causing the switching means to connect the charge storage means to the ignition device at engine speeds above a predetermined level to provide an advance spark at the ignition device.

10. The ignition system of claim 1 in which the rotatable part of the engine comprises a flywheel of the engine and the portion of the magnetic circuit means on the rotatable part comprises at least one permanent magnet supported by the flywheel.

11. An ignition system for an engine employing at least one spark gap ignition device, comprising:

charge storage means;

first means for generating a series of voltage pulses of one polarity in synchronism with operation of the engine and for applying them across the charge storage means; switching means responsive to a control signal to connect the charge storage means to the ignition device;

second means for generating a control signal comprising pulses recurrent in synchronism with engine operation;

third means for generating a control signal comprising pulses recurrent in synchronism with the engine operation; and

means for applying the control signals of the second means and the third means to the switching means to cause the switching means to connect the charge storage means to the ignition device for enabling the control signal of the second means to actuate the switching means during engine operation to a predetermined speed and the control signal of the third means to actuate the switching means during engine operation in excess of the predetermined speed to provide an advance spark at the ignition device.

12. The ignition system of claim 11 in which the first means comprises magnetic circuit means and a first wind ing cooperable with the magnetic circuit means for generating voltage pulses therein, and first rectifier means for connecting the charge storage means to the first winding to charge the charge storage means by current of one polarity flowing in the first winding.

13. The ignition system of claim 12 in which the second means comprises a second winding cooperable with magnetic circuit means to generate a control signal, and second rectifier means for connecting the second winding to the switching means to have one polarity of the control signal applied to the switching means to cause the switching means to connect the charge storage means to the ignition device.

14. The ignition system of claim 13 in which the third means comprises a third winding cooperable with magnetic circuit means to generate a control signal, and third rectifier means for connecting the third winding to the switching means to have one polarity of the control signal applied to the switching means to cause the switching means to connect the charge storage means to the ignition device.

15. The ignition system of claim 14 in which the first, second and third windings cooperate with the same magnetic circuit means, the magnetic circuit means comprising at least one permanent magnet adapted to be mounted on a rotatable part of the engine to travel along a predetermined path; and in which the first winding is supported on a non-rotatable structure and positioned along the path to be cooperable with the magnet for having the voltage pulses generated therein, the second winding is supported on a non-rotatable structure and positioned along the path to be cooperable with the magnet for having its control signal generated therein, and the third winding is supported on a non-rotatable structure and positioned along the path of travel of the magnet at a position in a range extending between and including the positions of the first and second windings to be cooperable with the magnet for having its control signal generated therein.

16. The ignition system of claim 15 in which the means for regulating the control signals of the second winding and third winding is provided by having the third winding of fewer turns than the second winding and the third winding having its control signal generated therein after the first winding and before the second winding.

17. The ignition system of claim 15 in which the rotatable part of the engine on which the at least one permanent magnet is mounted comprises a flywheel of the engme.

18. The ignition system of claim 17 in which the magnetic circuit means has two permanent magnets mounted on a flywheel of the engine to cooperate in producing pulses in the windings.

19. The ignition system of claim 18 in which the first winding is wound on the center leg of a generally E-shaped stator member which has its legs positioned along the path of travel of the permanent magnets for having voltage pulses induced in the first winding each revolution of the flywheel.

20. The ignition system of claim 15 in which a separate stator of magnetic material is provided for each winding and the windings are arranged along the path of travel of the magnet such that the magnet generates a pulse in the first, third and second windings, successively.

21. The ignition system of claim 15 in which the second and third windings are wound on a common stator of magnetic material.

22. The ignition system of claim 14 in which the means for regulating the control signals of the second winding and third winding is provided by having the third rectifier means include a Zener diode.

23. The ignition system of claim 14 in which the means for regulating the control signals of the second and third windings is provided by having the third winding of fewer turns than second winding and by having the second and third windings wound on a common stator of magnetic material in opposite direction.

24. The ignition system of claim 1 in which the first winding is supported on a first portion of the magnetic circuit means on the non-rotatable structure, and the second winding is supported on a second portion of the magnetic circuit means on the non-rotatable structure spaced from the first portion along the path of travel of the rotatable part.

25. The ignition system of claim 1 in which the portion of the magnetic circuit means on the rotatable part comprises magnetic flux generating means.

26. The ignition system of claim 14 in which the second and third windings cooperate with the same magnetic circuit means.

References Cited UNITED STATES PATENTS 3,240,198 3/1966 London et a1. 3,311,783 3/ 1967 Gibbs et al. 3,324,841 6/1967 Kebbon et al. 123-149 3,358,665 12/1967 Carmichael et al.

LAURENCE M. GOODRIDGE, Primary Examiner U.S. Cl. X.R. 

